Tuberculosis (TB), one of the most widely spread diseases in the globe today, has infected one-third of the world's population. In 2006, 9.2 million new TB cases were reported, with 1.7 million related deaths, mostly in developing countries. In 2006, approximately 15,000 new TB cases were reported in the United States. Because a patient with active but untreated TB can infect on average between 10 and 15 people per year, the prompt diagnosis of new TB patients is essential to effectively control the disease.
Currently, there are multiple techniques for TB diagnosis. However, none of the available methods have a superior combination of low detection limits, analysis time, and cost. Those techniques with low detection limits are time consuming, while relatively fast tests have high detection limits and typically need to be verified eventually by a (slow) assay. Despite mature technologies for testing TB, improved detection methods are required to address the disease on a global scale.
Another analyte of interest is extracellular DNA, which is of great interest in the fields of disease diagnostics and environmental molecular biology. Unlike the genomic DNA in living cells, extracellular DNA is the free DNA released from dying cells. Thus, extracellular DNA circulating in body fluids can be used as an early indicator for various acute diseases such as cancer. For example, the concentration of extracellular DNA for a healthy person is about 30 ng/mL, but the concentration is increased to about 300 ng/mL for a cancer patient.
For environmental monitoring, extracellular DNA dissolved in lakes and soil is an indicator of environmental quality because the dissolved DNA is generated from cell lysis and excretion from living organisms.
Despite great interest, the study of extracellular DNA is hindered by the standard sample preparation methods currently utilized. The conventional method begins with filtering, centrifuging, and collecting DNA from a raw sample. Several hours are typically required for the sample preparation process, which can degrade and mutate extracellular DNA. As a result, the original information of extracellular DNA is partially or completely lost prior to analysis. Therefore, a rapid process that can concentrate extracellular DNA is very important for identifying pathogenic information.
The above examples of TB and extracellular DNA are scientifically significant analytes that are currently tested using methods that are slow, inefficient, and inadequate. An improved method for extracting particulate analytes, such as TB and DNA from a solution would provide a great benefit to global heath by improving the efficiency, cost, and accuracy of tests for diseases such as TB and cancer.